I noticed that about a week ago, binance was listing LTC, ETH, and BTC at prices roughly 10% lower than Gdax did.On binance, BTC = $1k USD cheaper, ETH = about $50 cheaper, LTC, about $30 cheaper.
Today, this gap has been closed to less than 5% price disparity between the 2 exchanges in LTC, ETH, and BTC.
What is the reason for this? Is it globally economic factors, such as a change in exchange rate ratios between major currencies?
GDAX is the exchange for coinbase, and coinbase is the largest and easiest way for US residents to buy BTC, LTC and ETH. because they are the biggest "gateway" for fiat money to enter the system in the US (and probably the west on the whole), their prices sometimes pump much higher than other exchanges.
for example, on 12/6 the BTC price reached $19,340 on GDAX. it only reached $16,649 on bitfinex. that huge difference boils down to dollar-heavy traders on GDAX vs. other exchanges. it's much easier to get $$ onto GDAX than bitfinex. so basically, when there are massive amounts of fiat money trying to enter the market, the prices will be higher on GDAX. due to arbitrage, this premium spreads to any markets they offer (LTC, ETH).